Arena Pharmaceuticals Inc. CEO Amit Munshi said the $800 million up-front, worldwide licensing deal with United Therapeutics Corp. centered on prostacyclin (IP) receptor agonist ralinepag in pulmonary arterial hypertension (PAH) "allows us a broader push in the GI [gastrointestinal] space" with S1P receptor modulator etrasimod, which has reached the planning stage for phase III trials in ulcerative colitis (UC).